Safety clutch release



Oct. 25 1.927. 1,646,458 l R. H. PRATT SAEETE CLUTCH RELEASE Filed Dec. 4. 192e 2 she's-sheet 1- A r 5 I l VMss* HPRAT'T.: *i* @M oct. 2s, 192.7. 1,646,458

R. H. PRATT SAFETY CLUTCH REL-EASE Filed Decj4. 192s -2 sheets-sheet 2 me/nto@ R oss H @MTT @QMS-@W Patented Oct. 25, 19127. i

Ross; PRATT, or' WASHINGTON, DIsTnicT or COLUMBIA.v

n SAFETY CLUTCH RELEASE. j

Application ledf' D'ecemb'er, 192,67. Serial No. 152,650. l

Thisv invention relates to safety clutch release mechanism and more particularly to safety clutch releases especially designed for use' in connection ivithfvvorm-driven poiver transmissions. l It is a major purpose of the present in vention to provide agnovel clutch release, particularly designed for the aforesaid Worin-driven transmissions, adapted toau-A tomaticallfy operate upon any undue stress being had betiveen the driven 'Worm-gear and* the driving Worm.

ln Worm-driven power transmission, Where a drive shaft or drivingmemberisprovided with a Worm adapted vto meshy or engage with a Worm-gear carried 4by tliexdriven member, ifj for any reason the motive power suddenly ceases,` the momentum of' the driven memberresults in a further rotation oi the worm-gear thereon With the resultant excessive end-thrust of the teeth on such gear against the teeth of' the drive Worm; this resulting, unless the. driven` member is brought to an immediate stop` in the damaging' or strippingr of the teeth on either the Worm or-the Worm, gear.` t

In an effort tosai'feguard against this', in the great majority' of transmissions type, driving Worms are employed h-aving an exceedingly steep pitcli and upon vthe rel moval of the kmotivepowen the teethf ofthe Worm-gear contact With the relativelysteep,l inclined sides of the teeth on the drive-Worm thus'y permitting of coasting Withouty any Cil driving-)Worm of'l'oWer pitch, the teeth there onzivould lie in a vplane more perpendicularl with respect to the teeth onthe Worm-gear. f This is most particularly' true ot the present 40 types otworm-d'riven transmissions or drives used in connection with motor vehicles,

Where the driving-Worm is provided With ar' pitch generally in excess of thegreatest` power may be impartedV to the driven mem-` ber with a great deal more facility.

lt 'is accordingly a major purpose ofthe present invention to provide a safety clutch y release which will l permit of the usel of' Worms of any desired pitch in power trans-V missions of the class described, and which 5 ing had toi the Worms or WormH gears throughmotive power. Obviously with the use'ofa` will obv-iate any possibilityl ofd'amage be other cause. l I

rlhe invention liafsgbce'n illustrated and described in the drawingsV 'as partica]arly" adapted `to the novel transmission ofy thel Worm-.driven type described and claimed a co-pending application filed by` the ventor under date of October 2nd', V1926, and'vv bearing Seri-al Number 139,170; itl "being understood that such illustration isrneifelfy v illustrative of one' embodiment of the inverte* tion and is not in anyyvay limitative`inasmuch as application thereofmightl beas convenient-Wheel with vany other type ofwverrn-f driven povver transmission.

In particular the invention provides novel mounting of the vdriveivorm upon the" end-'thrust as above described or through any drive shaft, novel mechanism and connfee@ tions between said worin and theclutch of' the transmission, and novelfnieans for' aetuating suc-h mechanism to automatically r'e'- lease said clutch should"conditions require saine."V Further oliject-sfoi;` the invention Will be hereinafter m'oreiully set forth.

so Theaccoinp anyi-ng Y drawings illustrate onef practical transmission, of the Worm-driven' type, Whi'chwill be described in detail'to ena-ble' o thers'to understand and: use the same,'but Vthe invention is not consideredv restricted to the specific construction shown in thedrawings, and reference is therefore'` had to the"V embodying' the present iiiverli`tior 1,v

claims forsummariesv ofthe essentials of thel struction j and' novel combinations of for all of Wli'ic'hprotect-ion is desired. v

A s shown inthe 'drawings operative or engaged position.

mounting of the drives-Worm thereon, illus--A trating the same in operativ-e or' engaged position.

Figure' 3l 'isav view similar t'o Figure 2 illustrating in elevation, .the drive-Wormand associated mechanism in disengaged posi-V tion.

Fig'purerl isa sectionalA vie-W through` ant entire Worm-driven transmission', parts bebaing broken away, illustrating the same' inf the entiretransmission taken on tlife ,Figure2' is alongitudinal sectional vi'ei'v i through thev drive shaft illustrating the novel Y Figure 4 vis a fragmentary detail sectionaly K invention and of the novel features of coli-, ,99 y

parts? view taken onthe line 6 6 of Figuren illustrating one form of actuating lever in disengaged position. c c c Figure 7 is avieiv4 siii'iilai-*toFigure 6 illustrating the actuating lever in engaged position.

Asshoivn in the drawings there is provided a driving member or drive shaft S of'axi'ally aligned axles or shafts 6 having theirlinner extremities terminating in the usual differential (not shown) mounted Within they usual diferentii-il housing 7.

...A suitableliousingrorA casing() is provided for` ,therearend, `such housing prefera-bly formingr an `integral part of a-casing` surrounding the drive shaft and the drive- WormA and associated mechanism thereon.

Suitable bearingsb, of an;1 desired type and only one of which has been illustrated. are provided for the :proper support and align `ment of the `shafts `or axles. The differential ,housing 7 is provided. at one side thereof with an integralsleeve extension 7a. surrounding the axle 6, and upon which is mounted for free rotation the driving Woringearf8. i Y

i The gear 8 `preferablyhas associated there-` with a suitable clutch otra-ny desired type `rfoperly mounted-upon thevsleeve 7a. There llas been illustrated in the drawings the `usual type of disc clutch,` comprising `the usual outer drum preferably forminr an integral part of the `Worm-gear 8, inner drum keyed orotherwise secured to the sleeve extension 7*, the discs, clutch push ring, driving'pla'te and clutch fingers.. all as are ivell known in the art and needino further description here.

Y Obviously any othersuitable type of clutch might be as conveniently used. The clutch 8%is adapted to beheld in engaged position Y by the pressure of a-coil springr 8? interposed bet-Ween a recessed lock-nut 8 secured upon the sleeve 7a "adjacent the extremitytliert-iofAv and a clutch shift ring:` 8g freely mounted upon the said sleeve. `The clutch `shift ring` is provided with a centrally located turneddovvnportion adapted for engagement with the inturned extremities 9c of a `clutch-fork 9b secured toaI counter-shaft Qjournalled within suitable bearings 9 on the inner face of` the ktransmission housing. It ivill be readily understood that movement of the clutch fork in a clock-Wise direction with relation to the'mountingthereof on -the counter-shaft 9 `will result in the lateral movement 'of the Aclutch shift ring ivith the resultant compression of the. coil spring S and the release or dsiengagenient of the clutch 8d, thereby freeing the \voringear S and permitting` the same to come to rest or rotate independently of the driven shafts and associated parts of the driven member.

The drive-'worm l is retained in proper position upon tliedrive shaft 'between col`V lars 2 and 3 mounted adjacent thereto upon said shaft. The collar 2 isrigidly secured against endivise movement upon the shaft as by a pin 2a or other suitable means, While the .collar 3 is loosely mounted upon such shaft. and is retained against the adjacent end of Athe V.drive-Worm bv a coil spring 3 mounted upon the drive shaft betiveeirthe` collar 3 and acollar 4 also rigidly secured Y upon said shaft against endivise movement.

as vby a pin 4 or other suitable means. The.

tension of the coil `springagainst the drive i Worm through the collar l3,' is sufficient under normal conditions of operation to retain the drive-Worm `against the collar` 2, in proper position for driving engagenientiwith the Worm-gear 8. Y Rotation of the drive shaft S 4Will result.

through the Worm 1 and Worm-gear 8, in the rotation of the driven member. Should the motive power suddenly cease, for any reason, the drive shaft andavorm thereon would immediately come torrest While the momentum of the driven `member would tend tocontinue the rotation of the Wormfgear thereon. As ajresult of `such continued 'rotation the teeth on the worm-gear vWould be I. forced `against the relatively perpcndicularly l disposed faces of the teeth onfthe drive-Worm and the pressure thus exerted 'vvouldresult `ing-the lateralmovement ofithe said drive? Worm tothe position illustrated in Figure 3.

of-thedra-Wings for a'purpose to be'hereiii` after more fully described-` i The `movable collar 3 is provided adapted for engagement with the `forkb of ashifting member orlever 5 .tixedly se-` with centrally located turned down portion 3l" iio ou-redto a `'shaft 5 pivotallyfmounted ivithiin suitable bearings within the transmissionV housing. "Ajdoivnwardly depending lever 5c iscgalso ixedly securedrto the shaft `.5",

preferably in approximate alignment with the V clutch fork 9h above referredto, and

has at its lower-extremity connection with` an` actuating lever 5f through a .linku` Theactuating lever 5e is `adapted -to contact Withfthe inner face `of. thefclutch fork 9b and is provided with a Wedge-.shaped cam-` l likeportionft for a-purposeto Vbe .herein-` after'llore fully described.` The levereis maintained in properpositionabutting the.v `clutch fork by any suitable meansyas by resting Vupon an extension or shoulder-5g,

formed on the inner face of the clutch fork and by being retained c. against.. side-Wise movement by a roller 51? journalled Within a standard 5k formed vintegrally with or secured to the'casing C (see 'Figure 5 of the drawings).

In the normal position of the actuating y lever, thefcain-lile portion f thereof will the levers n'and' 5, in a rearward move-r ment of the actuating lever 5e and through the wedge-shaped cam thereon the clutch forli 9U`will be moved suiiiciently to disen-y l gage tlie'clutch 8d. Immediately upon the release of such clutch the worm gear t3y will be freed from any rotative force or momentum andi'will be immediately brought toa position atrest, thus eliminating any pos,- sibili-ty of damage to either the drive-worin or driven worm-gear. The tension of the spring 3 should be suiiicient -so as not to permit of the, release ofthe clutch as aboveV y described and thereby permit a vehicle descending a grade to travel more rapidly than the governing speed set for it by the driving worm rotating in either first or second speeds. i

It has been found in actual practice that the aforesaid mechanism may be so adjusted as to relea-se the clutch only suiiiciently to prevent breakage, retaining as much friction in the clutch as possible to act as a braking element to check the momentum and slow down the movement of a vehicle equipped with worm-driven transmission constructed in accordance with the presentinvention.

lhile in the embodiment of the invention illustrated, the clutch has been shown and described 'in conjunction with and formingA a part of the driven worm-gear, it will be clearly understood that such disclosure 'is only illustrative, the invention being just as applicable upon merely a variation of'connecting link and actuating lever, to operate directly upon the usual engine clutch to be found in automobile transmission construe'- tion, or the usual clutch to be found inl any type of worin-driven power transmission.

Obviously any type of operative meclianism or connection might be had between the drive-worin and the clutch whereby upon utilization of the essential feature of the present invention, i. e. the resilient mounting of the drive-worm so that undue stress thereon will result in a lateral movement thereof, such movement would result through the aforesaid mechanism in the immediate disengagement of the said clutch'.

There has thus been described a clutch release especially designed for use in connection with worm-driventypes of power transmissions, adapted to automatically op# crate upon any undue stresser strain being had between the driving-worm. andv then driven worm-gear.

I claim:` 1 Y Y' l. A power tra-emission `of theclass de'- scribed' ineluding'dri'ving anddriveng'mem`V bers, operative connection therebetween comprising a worm-gear carried by the drilv-'f en' member adapted for engagementwifth al drive worm carried by the driving member and longitudinally movable thereon, a clutch connection between y saidL worm-gear andthe driven ii-iembe'r, and operative connectionsl between the drive-worm and said clutch to disengage the; clutch upon Jlongitudinal inoveifnentof; the worm.

2. A power transmission of' the class described including driving and driven inem#y bers, operative connections therebetween comprising a worin-gear'carried by the 'driven member vadapted for engagementwi-th a drive worm carried bythe 'driving member and?" longitudinally movable 'thereon upon predetermined stress between they worin-gear and the said drive worm, "a clutch connection betweeny said worm-gear andthe driven member, and operative connections between the drive worm and thesaid clutch to disengage the clutch upon longitudinal movement of the worm. l

3. A power transmission of the class de-` scribed including driving and driven members, operative connections therebetween comprising a worm-gear carried Aby the driven member adapted for engagement with a drive worm carried by the driving member and longitudinally movable thereon upon predetermined stress between the worm-gear and the said drive worm, a clutchv connec- Sill tion between the worm-gear and the driven member, operative connections between the drive woimand thesaid clutch operable to diseiigage the clutch upon longitudinal movement of the worm, and means for returningthe drive yworm to its normal position and simultaneously re-engaging the clutch. ,K

4. In a power transmission of the class described, in combination, driving and driven members, operative connection therebetweenY comprising a worm-,gear carried by thev driven member and adapted for engagement with a drive worm carried by the driving member and longitudinallymovable thereon upon predetermined stress between the said worm-gear and drive worm, a vclutch connection between said worm-gear and the driven member and a clutch fork adapted toact-nate said clutch, operative connections between the drive worm and the clutch operable to disengage the clutch upon longitudinal movement of the drive worin comprising a reciprocable. lever having a wedge-shaped cam-like portion adapted to engage with the llt) aforementioned clutch fork, and` L resilientV means for returning the drive worm` to `its normal position and simultaneously re-en gaging the clutch.

i 5. In a power transmission oi the Class deseribed,` in eombinatiom a driving member driving a driven memberat a predetermined ratio` of Speed, a clutch, operative connection between the driving memberand theelnteh for controlling the said clutch, and means responsive to the relative speeds of rotation of the driving and driven membersfor automatieally `releasing; the clutch upon the speed of rotation of the driving member falling below the aforesaid predetermined ratio. 6.` In a power transmission of the class described, in combination, a driving member drivinga driven memberata predetermined ratiofof speed, operative connections therebetweencomprising a drive worm earried byfthe drivingmember adapted for engagementwith a worm-gear carried by the driven member7 a clutch connection betweensaid worm-gear andthe Vdriven member, opera* tive connection between the driving member andthe leluteh for controlling the said clutch,` and means responsive to the relative speeds of rotation of the driving and driven `members for automatically releasing the clutch npon `the speed of rotation Vof the driving member falling below the aforesaid prede-` termined ratio. v

7. In a power transmission ofthe class described, in combination, driving anddriven Y `of the driving and driven'members for au-` tomatieally releasing the clutch u on the speed of rotation ofthedrivingmem er fallingr below `its proper ratio to; thatlof the driven` member, and means for reengagin0` the clutch` upon the proper lrelative spee ratiobeing resumed.` In `testimonywhereof he' affixes his signature. i

RossH; PRATT. I e, 

